Microcontroller-based acquisition system for evoked otoacoustic emissions: Protocol and methodology

This work presents the development of a signal acquisition and processing system for the fast detection of Transient-Evoked Otoacoustic Emissions (TEOAE). It was built under IEC 60645-6, IEC 62304, and IEC 82304-1 standards. Hardware and firmware specifications based on a Cortex-M7 microcontroller and an ER-10D acquisition probe are presented. A user interface was designed for parameter configuration and monitoring the detection process in a host personal computer. The signal processing chain is presented, and a time-frequency binary-mask approach is proposed to increase the signal-to-noise ratio, leading to a significant decrease in the average detection time. Results obtained with the implemented prototype for two different detection strategies were compared with those from a commercial equipment. Screening tests were performed with eight volunteers and one neonate with normal hearing. On average, the proposed hardware and associated signal processing methods provided a detection time fourteen times faster than the analyzed commercial system. These results are of special interest to developers of TEOAE screening systems.